[Moved to Hardware Forum]
I would like to speed up the rendering process adding another GPU to the system using an Nvidia Quadro 4000 MAC installed with a Sonnet Echo Express PRO:
I'm pretty sure that's not going to work for a number of reasons. First of all: OS X doesn't have drivers in its kernel (or available aftermarket) to address a GPU via the Thunderbolt port. It's not clear anyone has even considered writing those because of the (lack of) speed of the Thunderbolt ports.
Second is power. The Quadro needs a 6-pin PCI-E connector from the power supply in order to work properly. I looked through the technical specifications of that device and didn't note any mention of providing PCI-E power connectors. And given the power supply, (100W or 150W), it's not clear it even could.
All isn't lost, however. Assuming you have the right MBP with a 1GB nVidia GPU, you can still enable hardware MPE with the text file edit. Hunt around for instructions on how to do that edit; you can do it with your existing installation of PPro (and I'd recommend staying there vs 6.0 for the time being).
Thunderbolt has the equivalent Bandwidth of a PCI-E Gen1 4X slot or Gen 2 2X bandwidth. This is really low for a video card device. I would not recommend it.
You just educated me, I was all enthused with the new Gigabyte motherboards that have a pair of Thunderbolt interfaces that I was thinking of for external disk drive arrays.
Thank you for your answers.
I think everything is now clear.
I'll keep my system as it is now.
Thank you very much